Add phrase marks (ligature)

[sertansenturk]

The vocal pieces in the SymbTr collection consist of phrase marks (big "ties" spanning several notes), which indicate the groups that should be sung "together". In txt files these marks are shown in the LNS column starting with the value 99. It continues in the next notes again with the same value (99) until LNS becomes 95. Hence the LNS sequence of the the notes in a phrase mark is "99 99 99 ... 99 95". We should add this information to the scores.